Rep. Shelley Moore Capito of West Virginia announced Monday that she will run for the Senate in 2014, immediately putting a solid Democratic seat in play for Republicans and turning the spotlight on incumbent Sen. Jay Rockefeller.

The 75-year-old Rockefeller, a West Virginia institution first elected to the Senate in 1984, declined to reveal whether he plans to run for re-election. And the contours of the West Virginia Senate race would look vastly different if it’s an open-seat race instead of a contest pitting Capito — whose popular father served three terms as governor — against Rockefeller, a former governor who has funded past campaigns with money from his deep personal fortune.

“If he runs, it’s going to be a very close race. If he retires, Shelley’s got it in the bag,” said one Republican operative with significant experience in West Virginia.

That’s the conventional wisdom, at least, which makes the senator’s decision all the more important. In a statement, Rockefeller was mum on his intentions.

“[E]veryone I talk to in West Virginia is tired of the nonstop campaigning,” he said. “West Virginians just want us to do our jobs, and for me that means focusing full-time on the serious issues at hand. Politics can wait.”

Neither side may stand still, however. Operatives of both parties, from Charleston, W.Va., to Washington, D.C., were already trying to game out what Rockefeller might do and how the race would shape up.

And Capito, in the speech announcing her candidacy Monday — also her 59th birthday —not-so-subtly put the ball in his court.

“I have decided to make my political intentions for 2014 known now so that I can get back to work in Washington and avoid disruptive political speculation,” she said, according to prepared remarks. “It will also hopefully provide clarity and time for others to make decisions.”

Some Democrats saw signs that Rockefeller was inclined to try for a sixth term.

“He made an awful lot of calls on election night to winners and losers and movers and shakers,” one Charleston Democratic operative said. “Why would you do that if you’re retiring?”

“My best guess is that Rockefeller stays and wins,” emailed a plugged-in Democratic operative familiar with the Senate landscape.

If Rockefeller does decide to run, Republicans familiar with the state expect him to start out with a lead, given his strength among the base of his party in a state where Democrats hold a registration advantage.

But Capito is popular, has cross-party appeal, a record that’s in tune with the state and was on the right side of the presidential election. Every county in West Virginia voted for Republican Mitt Romney over President Barack Obama in the 2012 presidential election. The Republicans have won every presidential election in West Virginia since 2000, but the Democrats remain the stronger party in this culturally conservative state, maintaining its hold on the governorship and the Legislature during this same period.

“I think it’s going to be a knock-down drag-out if it’s the two of them,” a West Virginia Republican said. “It’d be a bruising campaign.”

Indeed, Roll Call has learned that there are already conversations going on in GOP circles in the state about independent expenditure efforts to hit Rockefeller.

A potential line of attack would be on his recently evolved positions on coal — not always in line with the companies that operate in the coal-heavy state.

“It’s no secret that Sen. Rockefeller has a more liberal posture on coal,” Republican pollster Mark Blankenship said. “That’s not necessarily going to be a catch-all strategy for the Capito campaign, but in the southern coalfields,” he said, it could swing voters to her and “chew into that Democrat firewall.”

If Rockefeller decides to retire, Democrats appear to have a relatively limited bench of tested statewide elected officials. Two potential candidates: Democratic Gov. Earl Ray Tomblin and state Supreme Court of Appeals Justice Robin Davis, who both just won statewide office this year.

Capito, who is far from a conservative’s conservative, could also face primary challenges.

The pro-free-market Club for Growth sent out a statement Monday morning blasting Capito. Club President Chris Chocola noted what he called her “long record of support of bailouts, pork and bigger government.” The Senate Conservatives Fund political action committee associated with Sen. Jim DeMint, R-S.C., also sounded a critical note against Capito.

But West Virginia GOP insiders don’t expect the primary electorate to be favorable to a candidate other than Capito. And it doesn’t hurt that she’s staked out her position early. The only name floated by Republican insiders as a potential primary challenger was frequent candidate John Raese, who most recently lost to Democratic Sen. Joe Manchin III by 24 points. Raese also lost to Manchin in a 2010 special election.

But in an interview with Roll Call, Rep. David B. McKinley, R-W.Va., who just won his second term, didn’t rule out a Senate bid.

“I think all options ought to be out there,” he said. “It’s very early for someone to start a campaign at this point.”

And McKinley offered what could be construed as a veiled criticism of Capito.

“I’m a little surprised that that race has kicked off so early. I would think that it would be in everyone’s best interest to let the people absorb the impact of this past election,” he said.

Democrats, not surprisingly, also knocked Capito’s early entry.

“I think it signals she’s a little worried about other people getting into the race, so she moved up the time frame,” said a Senate Democratic operative familiar with West Virginia.

A Capito aide brushed aside the criticism and said the congresswoman is focused on doing her job in the House and focusing on the essentials of the early part of a Senate campaign.

“Right now, we’re going to focus on raising money and talking about why she wants to represent the people of West Virginia in the Senate,” Capito campaign adviser Kent Gates said. “We’ll see who our opponents are.”